You may also find https://github.com/Canop/bacon to complement this type of workflow / mental mode. I keep both bacon and cargo-watch installed and use each regularly but I probably spend more time with bacon for commonplace working sessions.

Also in the ring are https://github.com/eradman/entr and watchexec (which shares code and authorship with cargo-watch IIRC). As you can see I'm a fan of changed-files-automatically-do-things workflows.